Wells are drilled to extract oil and gas from subterranean reservoirs. Oil and gas typically enter the well from the producing reservoir through perforations in the well casing. Initially, the reservoir pressure may be sufficient to overcome the force of gravity and force oil and gas out of the well. As the reservoir pressure decreases, however, fluids may accumulate at the bottom of the wellbore and it may become necessary to employ artificial lift systems to harvest the oil and gas. Examples of artificial lift systems include surface-mounted sucker rod pumps, electrical submersible pumps, plunger-lifts and gas-lift systems.
A plunger lift system works by cycling a well open and closed. During the open time, a plunger interfaces between a liquid slug and gas. The gas below the plunger will push the plunger and liquid to the surface. This removal of the liquid from the tubing bore allows an additional volume of gas to flow from a producing well. A plunger lift requires sufficient gas presence within the well to be functional in driving the system. Oil wells that produce no gas are not candidates for plunger lift recovery systems.
As petroleum products are drained from subterranean formations, the reservoir energy gradually decreases. In some cases, the reduced reservoir pressure allows water to accumulate and “load” the well. Gas wells that are loaded with water tend to produce poorly in intermittent slug flow or cease to produce at all. Artificial lift and stimulation procedures are often used to increase production from a loaded well. Chemical additives are often used to unload, or “de-water” the well. In recent years, it has become popular to inject “foamer” solutions down a capillary string to aid in the unloading of water accumulated in the wellbore. As gas passes through the foamer and water mixture, bubbles form and lift the water from the well. Foamers, or “soaps,” typically include a surfactant component that reduces the surface tension and fluid density of the water-well fluid mixture in the wellbore.
Current plunger lift systems, such as the plunger apparatus described in U.S. Pat. No. 7,513,301, only focus on the lifting of loaded liquids in wells. There is, therefore, a need for an apparatus and process for effectively and efficiently delivering foam-inducing chemicals or other well treatment chemicals to the loaded liquid to produce a foam thereby reducing the density of the liquid and subsequently increasing the functionality of the plunger.